ORE re-purposes the standard Faster R-CNN [1]} object detector with a ResNet-50 [2]} backbone. To handle variable number of classes in the classification head, following incremental classification methods [3]}, [4]}, [5]}, [6]}, we assume a bound on the maximum number of classes to expect, and modify the loss to take into account only the classes of interest. This is done by setting the classification logits of the unseen classes to a large negative value (\(v\) ), thus making their contribution to softmax negligible (\(e^{-v} \rightarrow 0\) ).
